Short answer: No.
Long Answer: You could run aircrack inside Debian (or Backtrack) on Android, but there is no way to redirect control of WLAN hardware to the Debian image, as of yet, so it would not work. Other than that, you'd need hardware and drivers capable of packet injection and monitor mode, as well as a version of aircrack-ng that has been rewritten to compile and run on Android (utilizing busybox, perhaps), which does not exist. This theoretical version of aircrack-ng would also need to be able to interface with the specific WLAN drivers involved.
That being said... who uses WEP these days, anyway?
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